Apparatus for directing fluids through a filter system

ABSTRACT

A fluid distribution system for directing fluids through a filter system. The fluid distribution system ensures proper distribution of fluids during the process of filtering as well as the process of washing a filter bed. The fluid distribution system may be used with numerous filter systems including but not limited to an upflow filter, a downflow filter, a combined upflow/downflow filter and/or multiple downflow filters connected in series.

FIELD OF THE INVENTION

The present invention includes one or more devices for directing fluids(i.e., a liquid and/or a gas) through a filter system for filteringwater and/or wastewater. The filter system includes but is not limitedto an upflow filter, a downflow filter, a filter system having acombined upflow filter and a downflow filter and/or a filter systemhaving multiple (i.e., more than one) downflow filters connected inseries.

BACKGROUND OF THE INVENTION

Various systems have been developed to filter water and wastewater.Typical filter systems include but are not limited to an upflow filter,a downflow filter, a combined upflow filter and a downflow filter andmultiple downflow filters connected in series. The term upflow filter isgiven to a filter in which the liquid or influent to be filtered isdirected in an upward path to remove impurities. Conversely, a downflowfilter is a filter in which the influent is directed in a downward pathto remove impurities. In a combined upflow/downflow filter, influent isdirected upwardly through the upflow filter to remove a predeterminedpercentage of the impurities in the influent and then the influent isdirected downwardly through the downflow filter to remove the remainingimpurities to within an acceptable limit. In this type of system, it iscommon for the upflow filter and downflow filter to include one or morelayers of filter media supported by one or more gravel support layers.Gravel support layers are necessary for certain filter systems toprevent clogging of the underdrain. For example, one common type ofunderdrain includes a plurality of underdrain blocks arranged inparallel rows across the bottom of the filter. The underdrain blocks actto direct and receive fluids including influent, effluent and air duringoperation of the filter system. The underdrain blocks typically includemultiple large apertures through which the fluids are directed andreceived. The apertures are of such a size that the filter media canpass therethrough and clog the underdrain block. This of course isdisadvantageous. One solution has been the use of one or more gravelsupport layers to support the filter media. The gravel is larger thanthe openings in the underdrain block and, therefore, does not passtherethrough.

However, gravel support layers have a number of disadvantages.Specifically, gravel support layers are expensive and time consuming toinstall. Further, gravel support layers consume a significant portion ofthe filter chamber thus reducing the filtering capacity of the bed.Also, gravel support layers are subject to being upset when uncontrolledair enters the filter bed due to improper installation of the air systemor operator error. Moreover, in filter beds using granular activatedcarbon such must occasionally be removed from the filter and placed in areactivation furnace. During removal of the granular activated carbon,the gravel becomes intermixed and is deposited in the reactivationfurnace. At the extreme temperatures necessary to reactivate thegranular activated carbon the gravel can explode damaging the furnace.

To overcome the disadvantages of gravel support layers, porous plateshave been used with underdrain blocks. The porous plates obviate theneed for the gravel support layers because they prevent the filter mediafrom passing through the apertures in the underdrain block. Typically,porous plates have been fastened directly to the underdrain block withscrews or bolts. This conventional means of securing the porous plate tothe underdrain block has significant drawbacks. These conventionalfasteners increase the cost of the system from both a materials andlabor stand point. Further, if the porous plate needs to be replaced alaborer would be required to removal all of the numerous fastenersbefore such could be accomplished. Moreover, conventional fastenerscould damage the porous plate requiring its removal. In addition, adirect connection of the porous plate to the underdrain block withoutsufficient offset would likely lead to maldistribution of the fluid.

To overcome the disadvantages of prior underdrain systems including butnot limited to the disadvantages attendant securing a porous plate to anunderdrain block with conventional fasteners Roberts Water Technologiesintroduced the novel and unobvious INFINITY™ continuous lateralunderdrain. This underdrain is prior art to the subject patentapplication as it was sold or offered for sale more than a year prior tothe filing date of the subject patent application. This underdrain isadvertised on the World Wide Web at www.robertsfiltergroup.com. Whilethe INFINITY™ underdrain is a significant improvement over previouslydeveloped underdrains, the present invention is yet a furthersubstantial improvement over the INFINITY™ underdrain. Specifically, oneaspect of the present invention includes a novel and unobvious means forpermitting a porous plate to be readily removed from a supportingstructure allowing replacement thereof. A significant advantage to thisaspect of the invention is that the porous plate can be removed from thesupporting structure readily without damaging the major components ofthe underdrain.

Another significant disadvantage of prior developments is that anexisting underdrain could not be satisfactorily retrofitted with aporous plate thereby obviating the need for one or more gravel supportlayers. Further, prior developments lacked the ability to readilyretrofit numerous different types of underdrains with a porous plate tothereby obviate the need for one or more gravel support layers.

Prior fluid distribution systems included means for distributing air toa filter bed having one or more layers of media during washing of thefilter bed. This is commonly referred to as air scouring. Air scouringhas been determined to be an important process in cleaning filter beds.A number of existing underdrain systems are designed such that liquidsand gases flow through common conduits. Such underdrain systems havesignificant drawbacks. Specifically, because of the conflict between theflow rates of liquids and gases, upper limits must unnecessarily beimposed minimizing the flexibility in setting different ranges of flowrates for liquids and gases. Further, common discharge passages forliquids and gases result in uneven discharge of the air bubblesresulting in undesirable maldistribution. To overcome the disadvantagesof prior underdrain systems including but not limited to thedisadvantages attendant common liquid and gas conduits, Roberts WaterTechnologies introduced the novel and unobvious ARIES® managed airsystems. This managed air system is advertised on the World Wide Web atwww.robertsfiltergroup.com. and disclosed in U.S. Pat. Nos. 5,535,202and 5,673,481. While the ARIES® managed air system is a significantimprovement over previously developed air scour systems, the presentinvention is yet a further substantial improvement as will be readilyrecognized by those skilled in the art.

Some previously known air scour systems have also suffered from thedisadvantage of maldistribution owing to incomplete evacuation of waterfrom the air conduit. The problem of incomplete evacuation of water isoften experienced where the air conduit has not been installedcorrectly. One example, is an unlevel installation of the air conduit.In such circumstances, the exit or discharge openings on the low side ofthe air conduit often remain blocked by water preventing properdistribution of air to the filter bed to adequately clean the same.

Previously known combined air and liquid distribution systems utilizingshared conduits have experienced uncontrolled releases of air which canlead to significant problems. Specifically, systems using sharedconduits are likely to experience rapid introduction of air or waterflow. This rapid introduction of flow can create a wave action resultingin fluctuation of the interfaces which can expose the water meteringorifices to air flow resulting in gross maldistribution.

OBJECTS AND SUMMARY OF THE INVENTION

An object of the present invention is to provide a novel and unobviousfluid distribution system.

Another object of a preferred embodiment of the present invention is toprovide a fluid distribution system which obviates the need for one ormore gravel support layers.

A further object of a preferred embodiment of the present invention isto provide a fluid distribution system which retains a porous platewithout the use of conventional fasteners such as screws and bolts.

Still a further object of a preferred embodiment of the presentinvention is to provide a fluid distribution system which permits readyremoval of a porous plate for replacement without damaging the majorcomponents of the fluid distribution system.

Yet still a further object of a preferred embodiment of the presentinvention is to provide a fluid distribution system which does notsuffer from maldistribution of liquids and/or gases.

Another object of a preferred embodiment of the present invention is toprovide a fluid distribution system which permits upgrading an existingunderdrain system to allow removal of one or more gravel support layerswithout removing the existing underdrain structure.

A further object of a preferred embodiment of the present invention isto provide a fluid distribution system which can be readily used inconjunction with numerous different exiting underdrains to permitremoval of one or more gravel support layers.

Still another object of a preferred embodiment of the present inventionis to provide a fluid distribution system which provides for separateliquid and gas distribution conduits.

Still a further object of a preferred embodiment of the presentinvention is to provide a fluid distribution system that permits an airconduit to be readily attached to an underdrain.

Yet another object of the present invention is to provide a fluiddistribution system which includes an air conduit having means forfacilitating evacuation of water from the air conduit.

It must be understood that no one embodiment of the present inventionneed include all of the aforementioned objects of the present invention.Rather, a given embodiment may include one or none of the aforementionedobjects. Accordingly, these objects are not to be used to limit thescope of the claims of the present invention.

In summary, one embodiment of the present invention is an apparatus foruse in a filter system for filtering water or wastewater. The apparatusincludes an underdrain. The underdrain has at least one chamber. Theapparatus further includes a porous plate and at least one supportmember for supporting the porous plate in fixed relationship relative tothe at least one chamber. The support member includes a weakness pointor other means for permitting ready removal of the porous plate. Anotherembodiment of the present invention is a method of enhancing an existingunderdrain of a filter system for filtering water or wastewater. Themethod includes the steps of providing an existing underdrain; providingan underdrain cap having a support member for supporting or receiving aporous plate; securing the underdrain cap to the existing underdrain;and, providing at least one porous plate to obviate the need for one ormore media support layers.

A further embodiment of the present invention is an apparatus for use ina filter system for filtering water or wastewater. The apparatusincludes an underdrain; an underdrain cap secured to the underdrain;and, an air distribution conduit detachably connected to the underdraincap. Still another embodiment of the present invention is an apparatusfor use in filter systems for filtering water or wastewater. Theapparatus includes at least one underdrain block and an air conduitdetachably connected to the underdrain block. Still another embodimentof the present invention is an apparatus for use in a filter system forfiltering water or wastewater. The apparatus includes an underdrain andan underdrain cap secured to the underdrain. The underdrain cap includesa recess or other means for receiving a porous plate.

Still a further embodiment of the present invention is an apparatus foruse in a filter system for filtering water or wastewater. The apparatusincludes at least one liquid distribution chamber and at least one airdistribution conduit. The apparatus further includes a porous plate. Theat least one air distribution conduit includes an exit opening disposedsuch that air exits the air conduit below the porous plate.

Yet another embodiment of the present invention is an apparatus for usein a filter system for filtering water or wastewater. The apparatusincludes at least one liquid distribution chamber and at least onedistribution conduit. The air distribution conduit includes an internalflange or other means for facilitating evacuation of water from the airdistribution conduit. Yet a further embodiment of the present inventionis an apparatus for use in a filter system for filtering water orwastewater. The apparatus includes at least one liquid distributionchamber and at least one air distribution conduit. The apparatus furtherincludes a porous plate. The liquid distribution chamber is disposedentirely below the porous plate. The at least one air distributionconduit includes upper and lower portions. The upper portion is locatedabove the porous plate while the lower portion is located below theporous plate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a first preferred embodiment of thepresent invention depicting two of multiple possible variations thereof.

FIG. 2 is a cross-sectional view of one of the two possible variationsdepicted in FIG. 1.

FIG. 3 is a cross-sectional view taken along lines 3—3 in FIG. 2.

FIG. 4 is a perspective view of the variation of the first preferredembodiment depicted on the left side of FIG. 1.

FIG. 5 is a cross-sectional view of two of multiple possible variationsof the first preferred embodiment of the present invention one of whichis depicted in FIG. 1 the other of which is not depicted in any of theprevious drawings.

FIG. 6 is a cross-sectional view of a second preferred embodiment of thepresent invention.

FIG. 7 is a cross-sectional view of a portion of the second preferredembodiment depicted in FIG. 6.

FIG. 8 is a cross-sectional view of one of the elements depicted in FIG.7.

FIG. 9 is a cross-sectional view of one of the elements depicted in FIG.7.

FIG. 10 is a cross-sectional view of one of multiple possible variationsof the portion of the second preferred embodiment illustrated in FIG. 7.

FIG. 11 is a cross-sectional view of one of the elements depicted inFIG. 10.

FIG. 12 is a cross-sectional view of one of the elements depicted inFIG. 10.

FIG. 13 is a cross-sectional view of a third preferred embodiment of thepresent invention.

FIG. 14 is a cross-sectional view of a fourth preferred embodiment ofthe present invention.

FIG. 15 is a cross-sectional view of a fifth preferred embodiment of thepresent invention.

FIG. 16 is a cross-sectional view of a sixth preferred embodiment of thepresent invention.

FIG. 17 is a cross-sectional view of a seventh preferred embodiment ofthe present invention.

FIG. 18 is a cross-sectional view of an eighth preferred embodiment ofthe present invention.

FIG. 19 is a cross-sectional view of a ninth preferred embodiment of thepresent invention.

FIG. 20 is a cross-sectional view taken along a different section of theninth preferred embodiment of the present invention.

FIG. 21 is a cross-sectional view of a tenth preferred embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The preferred forms of the invention will now be described withreference to FIGS. 1-21. The appended claims are not limited to thepreferred embodiments and no term used herein is to be given a meaningother than its ordinary meaning unless accompanied by a statement thatthe term “as used herein is defined as follows”.

FIGS. 1 Through 4

Referring to FIGS. 1 through 4, a fluid distribution system A isdepicted. The fluid distribution system includes an existing underdrainB, a pair of underdrain caps C and D and a pair of air conduits E and F.An air supply connection G is secured to the air distribution conduit Ein a fluid tight manner. An air supply connection H is secured to theair distribution conduit F in a fluid tight manner.

The existing underdrain includes a plurality of rows of underdrainblocks which are positioned on or adjacent the bottom of the filter.Only two rows are depicted in FIG. 1. The first row 2 of clay tileunderdrain blocks are disposed beneath the underdrain cap C. The rowsare formed by multiple underdrain blocks positioned in end to endrelationship. As is conventional, the upper surface 4 of each of theclay tile underdrain blocks includes a plurality of openings (not shown)through which fluid can pass. Each underdrain block in the first row 2includes four (4) chambers or conduits 6, 8, 10 and 12. Openings (notshown) are provided in the underdrain blocks so that chamber 10communicates with chamber 6 and chamber 12 communicates with chamber 8.The second row 14 of clay tile underdrain blocks are configured in amanner similar to the underdrain blocks in the first row 2 and,therefore, these underdrain blocks will not be described in detail.

The underdrain cap C is secured and sealed to the clay tile underdrainblocks via grout 16. However, it will be readily appreciated that anysuitable material may be used to secure and seal the underdrain cap C tothe underdrain blocks including but not limited to elastomeric sealants.Preferably, the underdrain cap C is extruded in continuous lengths fromhigh impact corrosion resistant PVC. Hence, the underdrain cap Cpreferably runs substantially the length of the row of underdrainblocks. However, it will be readily appreciated that the underdrain capC could be formed from any suitable material. Further, the underdraincap C may be sized such that multiple segments are positioned end to endto extend the substantially the length of the row of underdrain blocks.While the underdrain cap C is shown as running along (i.e., parallel to)the underdrain blocks, it will be readily appreciated that such could beoriented perpendicular to the underdrain blocks.

Referring to FIGS. 1 and 4, the underdrain cap C forms two conduits orchambers 18 and 20. Chamber 18 communicates with chamber 6 via theopening in the upper surface 4 of the underdrain blocks. Similarly, thechamber 20 communicates with the chamber 8 via the openings in the uppersurface 4 of the underdrain blocks. While two chambers are shown asbeing formed by the underdrain cap C, it will be readily appreciatedthat the underdrain cap C may be configured such that one or more thantwo chambers are formed. The underdrain cap C preferably includes a pairof horizontal walls 22 and 24 extending outwardly from recessed portion26. Walls 22 and 24 are provided with the appropriate number ofdischarge openings or orifices 28 to assure that the liquid flowing fromthe clay tile underdrain blocks is properly distributed throughout thefilter bed. When this embodiment of the present invention is used in anupflow filter, chambers 18 and 20 assure that the influent to befiltered will be uniformly discharged into the filter bed in the case ofan upflow filter. Further, when used in an upflow filter these chambersassure that the backwash liquid which may be either influent or filteredwater will be uniformly discharged into the filter bed. Similarly, whenthe present invention is used in a downflow filter, chambers 18 and 20assure that the filtered water will be uniformly collected and that thebackwash liquid will be uniformly discharged into the filter bed. Thisis a significant improvement of prior devices which mounted a porousplate directly to an underdrain block without any type of underdrain captherebetween.

The underdrain cap C further includes a pair of vertically orientedsupport members 30 and 32. Support member 30 includes a pair ofhorizontally extending elements 36 and 38. Elements 36 and 38 form arecess 40 for receiving a portion of porous plate 42. Verticallyoriented wall 43 supports the opposite end of porous plate 42.Similarly, support member 32 includes a pair of horizontally extendingelements 44 and 46. Elements 44 and 46 form a recess 48 for receiving aportion of porous plate 50. Vertically oriented wall 52 supports theopposite end of porous plate 50.

The air conduit E is snap fit onto the underdrain cap C. Specifically,the air conduit E has a pair of vertically extending walls 54 and 56.Each of the walls 54 and 56 have a pair of recesses 58. A pair of walls60 and 62 extend upwardly from the bottom of recess 26. The walls 60 and62 each include a pair of protrusions 64 for engaging the recessesformed in the corresponding walls of air conduit E. This configurationpermits the air conduit to be readily snap fit onto the underdrain capC. It will be readily appreciated that various other configurationscould be used to snap fit the air conduit onto the underdrain. In thisregard, it is noted that while walls 60 and 62 are depicted as being onthe inside of the corresponding walls 54 and 56 such orientation can bereversed. Air conduit E includes a pair of shoulders 66 and 68. Shoulder66 aids in securing porous plate 42 in fixed relationship relative tothe underdrain blocks. Similarly, shoulder 68 aids in securing porousplate 50 in fixed relationship relative to the underdrain blocks. Itwill be readily appreciated that porous plates 42 and 50 are held infixed relationship relative to the underdrain block without the use ofscrews or bolts.

Referring to FIG. 3, porous plate 50 has a plurality of grooves 70formed therein. It should be noted that while FIG. 3 depicts porousplate 50, porous plate 42 is configured in an identical manner. Achannel 72 is disposed in each of the grooves 70. The channels 72 ensureproper distribution of air or other gas along the width of the porousplates 42 and 50. It will be noted that the ends of the porous plates 42and 50 adjacent the air conduit E are spaced from walls 54 and 56. Thisspacing permits air or other gas to enter the channels 72.

The preferred embodiment depicted in FIGS. 1 through 4 prevents themixing of gas or liquids in chambers 18 and 20.

Rebar hook anchor 74 is disposed in the grout between the underdrainblocks to enhance securement of the underdrain caps C and D.

Referring to FIG. 2, underdrain cap D depicts one of many possiblevariations to the underdrain cap C. Underdrain cap D is similar tounderdrain cap C, therefore, only the differences will be explained indetail. Vertically oriented walls 76 and 78 have horizontally extendingelements 80 and 82, respectively. Further, vertically extending elements84 and 86 are disposed adjacent elements 80 and 82, respectively.Elements 80 and 84 form a recess to receive one end of porous plate 88.Similarly, elements 82 and 86 form a recess to receive one end of theporous plate 90. Unlike porous plates 42 and 50, porous plates 88 and 90directly abut the air conduit F. Metering orifices are provided in thechannels adjacent the air conduit F to permit air or other gas to enterthe channels and subsequently pass through the corresponding porousplate to the filter bed. It will be readily appreciated that other typesof openings other than metering orifices may be used. Air conduit F hasa different configuration from air conduit E. As will be appreciated byone of ordinary skill in the art, the air conduits may be configured innumerous different ways. The dashed lines F′ illustrates one suchpossible modification.

FIG. 5

Referring to FIG. 5, a fluid distribution system I is illustrated. Fluiddistribution system I is very similar to the fluid distribution systemA. Accordingly, only the differences will be described. Specifically,air conduit J has a different configuration than previously illustratedair conduits.

FIGS. 6 Through 9

Referring to FIG. 6, a fluid distribution system K is depicted. Thefluid distribution system K includes an existing underdrain L, a pair ofunderdrain caps M and N and an air conduits O. An air supply connection(not shown) is secured to the air distribution conduit O in a fluidtight manner to supply air or other gas to the air distribution conduitO. The existing underdrain L is as described in connection with thefluid distribution system A.

The underdrain cap M is secured and sealed to the clay tile underdrainblocks via grout 92. However, it will be readily appreciated that anysuitable material may be used to secure and seal the underdrain cap M tothe underdrain blocks including but not limited to elastic sealants.Preferably, the underdrain cap M is extruded in continuous lengths fromhigh impact corrosion resistant PVC. Hence, the underdrain cap Mpreferably runs substantially the length of the row of underdrainblocks. However, it will be readily appreciated that the underdrain capM could be formed from any suitable material. Further, the underdraincap M may be sized such that multiple segments are positioned end to endto extend substantially the length of the row of underdrain blocks.

The underdrain cap M forms four conduits or chambers 94, 96, 98 and 100.Chamber 94 communicates with the chambers in the underdrain blocks viathe openings formed in the upper surface of the underdrain blocks.Chambers 96, 98 and 100 communicate with chamber 94 via a plurality ofopenings 101 formed in horizontally extending wall 102. The underdraincap M includes a horizontal wall 104 which extends substantiallyparallel to wall 102. A plurality of openings 103 are formed in wall 104to permit fluid to pass from chambers 96, 98 and 100 upwardly throughporous plate 106. A pair of elements 108 and 110 extend upwardly fromwall 104 to support the mid-section of porous plate 106. End rails 112and 114 extend along opposite sides of the wall 104. Porous platesupport members 116 and 118 are connected to end rails 112 and 114,respectively. Support members 116 and 118 are configured in a similarmanner. Accordingly, only support member 116 will be described indetail.

Referring to FIGS. 7 through 9, support member 116 includes two separateelements 120 and 122. Element 120 includes a vertical segment 124. Thevertical segment 124 includes inner surface 126 and outer surface 128. Apair of members 130 and 132 extend inwardly from the inner surface 126.Members 130 and 132 form a recess for receiving a portion of porousplate 106 as is readily seen in FIG. 6. Members 134, 136 and 138 extendoutwardly from the outer surface 128. Members 134 and 136 receive aportion of end rail 112. Member 138 has a pair of protrusions 140 and142 as well as a weakness point 144. While weakness point 144 isillustrated as a V-shaped notch, it will be readily appreciated that theweakness point 144 can take many different forms. Further, it will bereadily appreciated that the weakness point can be formed in a varietyof different ways. Weakness point 144 allows removal of the porous plate106 without damage to any major component of the underdrain cap M.Specifically, one need only cut member 138 along the weakness point 144to readily detach the porous plate support member 120 from the porousplate 106. In this manner, the porous plate can be readily replaced.

Element 122 is substantially L-shaped and receives a portion of the endrail 112 as seen in FIG. 7. Element 122 includes a pair of v-shapednotches 146 and 148 which receive protrusions 140 and 142, respectively.Referring to FIGS. 10 through 12, an alternative form of porous platesupport member is illustrated. The porous plate support member 150includes two separate elements 152 and 154. Element 152 differs fromelement 120 in that the protrusions 156 and 158 as well as the weaknesspoint 160 are shaped differently. Element 154 differs from element 122in that the recesses 162 and 164 are shaped differently.

Referring again to FIG. 6, the underdrain cap N is formed in a similarmanner to underdrain cap M and, therefore, will not be described indetail. Air distribution conduit O is snapped onto pin 166. Pin 166 isepoxied into grout 168 or other suitable material. Rebar hook anchor 170is provided to enhance securement of the underdrain caps M and N to theunderdrain blocks.

Air distribution conduit O includes a plurality of water evacuationopenings 172 and a plurality of air distribution orifices 174. Internalflanges 176 and 178 facilitate the evacuation of water from the airdistribution conduit O.

Referring to FIG. 13, fluid distribution system P is similar to fluiddistribution system K depicted in FIG. 6. Accordingly, only thedifferences will be explained in detail. System P includes an airconduit Q. Air conduit Q has a pin 180 formed as one piece therewith. Acorresponding thin female element 182 is epoxied into the grout 184 orother suitable material. The pin 180 is snapped into female element 182.

FIGS. 14 and 15

Referring to FIG. 14, a fluid distribution system R similar to fluiddistribution system K is depicted. Accordingly, only the differenceswill be described in detail. Specifically, the fluid distribution systemR includes an air distribution conduit S. The air distribution S conduitis secured to or alternatively formed as one piece with elements 186 ofporous plate support members 188. Air conduit S includes two internalflanges 185 and 187 which facilitate discharge of water through thewater evacuation openings 189. Similarly, FIG. 15 depicts a fluiddistribution system T that utilizes another alternative air distributionconduit U. A plurality of laterals 190 extend outwardly from the airdistribution conduit U. The laterals 190 have a plurality of openings(not shown) to discharge air into the filter bed during air scouring.Air distribution conduit U is secured in a similar manner to airdistribution conduit S.

FIGS. 16 Through 18

Referring to FIG. 16, fluid distribution system V is similar to thefluid distribution system K with the exceptions that the air conduit hasbeen omitted and the existing underdrain is a monolithic wheeler bottom.In addition, a toggle bolt 192 may be used with or in place of the rebarhook anchor 194. Further, porous plates 191 and 193 may be provided withprotrusions 196 or 198 to provide additional support for the mid-sectionof the plates. Referring to FIG. 17, a fluid distribution system W,similar to fluid distribution system V, is being installed over anexisting nozzle underdrain. Referring to FIG. 18, a fluid distributionsystem X is mounted on a Trilateral air/water underdrain 199 via porousplate support members 200 and 202. Support members 200 and 202 areconnected to end rails 204 and 206, respectively. Preferably, end rails204 and 206 are formed as one piece with the Trilateral air/waterunderdrain 199. Support members 200 and 202 are similar to supportmember 116 depicted in FIG. 6, and, therefore will not be described indetail.

FIGS. 19 Through 21

Referring to FIGS. 19 and 20, fluid distribution system Y includes aone-piece underdrain 208, porous plates 210 and 212 and air distributionconduit 214. Porous plates 210 and 212 are similar to porous plates 42and 50. Underdrain 208 includes fluid chambers 216, 218, 220 and 222.Chamber 216 communicates with chamber 222 via a plurality of openings224 (only one of which is shown). Similarly, chamber 218 communicateswith chamber 220 via a plurality of openings 226 (only one of which isshown). Openings 228 are formed in upper wall 230 to permit fluids topass upwardly through porous plate 210. Support walls 232 and 234 extendupwardly from upper wall 230 to provide additional support for porousplate 210. Openings 236 are formed in upper wall 238 to permit fluids topass upwardly through porous plate 212. Support walls 240 and 242 extendupwardly from upper wall 238 to provide additional support for porousplate 212.

Underdrain 208 includes a plurality of air passageways 244 uniformlyspaced along its longitudinal axis. The left and right sides of airpassageways 244 are bounded by support walls 243 and 245, respectively.Support walls provide internal support for the underdrain 208. Airpassageways 244 are connected to air distribution conduit 214. An airsupply source is connected to the air passageways 244 to direct air toair conduit 214. Referring to FIG. 20, the underdrain includes verticalsupport walls 246. The vertical support walls 246 are positionedintermediate adjacent air passageways 244 and provide additionalinternal support.

Air conduit 214 is similar to air conduits E and F and, therefore, willnot be described in detail. Dashed line 214′ illustrates anotherpossible variation of the air conduit. It should also be noted that theair conduit could be formed as one piece with the underdrain orunderdrain cap.

Referring to FIG. 21, fluid distribution system Z is similar to fluiddistribution system Y and, therefore, only the significant differenceswill be described. Air is supplied to air conduit 248 in a mannersimilar to that depicted in FIG. 1. Accordingly, the fluid distributionsystem Z does not include internal air passageways that are utilized influid distribution system Y. The one-piece underdrain includes supportmembers 250 and 252 for supporting corresponding ends of the porousplates 254 and 256.

An air channel 258 is formed between support member 250 and wall 260 ofair conduit 248. Air channel 258 extends upwardly along the air conduit248 and allows air discharged from the air conduit 248 via opening 262to be released into the filter bed during the step of air scouring thebed to clean the same. Similarly, an air channel 264 is formed betweensupport member 252 and wall 266 of air conduit 248. Air channel 264extends upwardly along the air conduit 248 and allows air dischargedfrom the air conduit 248 via opening 268 to be released into the filterbed during the step of air scouring the bed to clean the same.

While this invention has been described as having preferred designs, itis understood that it is capable of further modifications, uses and/oradaptions of the invention following in general the principle of theinvention and including such departures from the present invention ascome within the known customary practice in the art to which theinvention pertains and as may be applied to the central featureshereinbefore set forth, and fall within the scope of the invention andthe limits of the appended claims.

We claim:
 1. An apparatus for use in a filter system for filtering wateror wastewater, said apparatus comprising: (a) an underdrain; (b) anunderdrain cap for retrofitting said underdrain with at least one porousplate, said underdrain cap being a separate piece from said underdrainand the at least one porous plate, said underdrain cap further beingsecured to said underdrain; (c) an air distribution conduit detachablyconnected to said underdrain cap, said air distribution conduit havingat least one shoulder for securing said at least one porous plate tosaid underdrain; and, (d) at least one porous plate.
 2. An apparatus asset forth in claim 1, wherein: (a) said underdrain includes anunderdrain block, said underdrain cap is secured to said underdrainblock.
 3. An apparatus as set forth in claim 2, further including: firstand second porous plates, said air distribution conduit having first andsecond shoulders for securing said first and second porous plates tosaid underdrain block.
 4. An apparatus for use in a filter system forfiltering water or wastewater, said apparatus comprising: (a) anunderdrain; (b) an underdrain cap for retrofitting said underdrain withat least one porous plate, said underdrain cap being a separate piecefrom said underdrain and the at least one porous plate, said underdraincap further being secured to said underdrain; (c) an air distributionconduit detachably connected to said underdrain cap; (d) at least oneporous plate; and, (e) said air distribution conduit having upper andlower portions, said upper portion of said air distribution conduitbeing disposed above said at least one porous plate, said lower portionof said air distribution conduit being disposed below said porous plate.5. An apparatus for use in a filter system for filtering water orwastewater, said apparatus comprising: (a) an underdrain; (b) anunderdrain cap for retrofitting said underdrain with at least one porousplate, said underdrain cap being a separate piece from said underdrainand the at least one porous plate, said underdrain cap further beingsecured to said underdrain; (c) an air distribution conduit detachablyconnected to said underdrain cap; (d) at least one porous plate; and,(e) said air distribution conduit having an exit opening where air exitsthe at least one air distribution conduit, said at least one exitopening is disposed below said porous plate.
 6. An apparatus as setforth in claim 5, wherein: (a) at least a portion of said airdistribution conduit extends above said at least one porous plate.
 7. Anapparatus for use in a filter system for filtering water or wastewater;said apparatus comprising: (a) an underdrain; (b) an underdrain capsecured to said underdrain, at least one fluid distribution chamberbeing formed between said underdrain and said underdrain cap, saidunderdrain cap having means for receiving at least one porous plate; (c)an air distribution conduit snap fit onto said underdrain cap; and, (d)a porous plate, said air distribution conduit having at least oneshoulder for securing said porous plate to said underdrain cap.
 8. Anapparatus as set forth in claim 7, wherein: (a) said underdrain includesa plurality of underdrain blocks, said plurality of underdrain blockseach having at least one fluid distribution chamber.
 9. An apparatus asset forth in claim 7, wherein: (a) said air distribution conduit has anexit opening where air exits the at least one air distribution conduit,said at least one exit opening is disposed below said porous plate. 10.An apparatus as set forth in claim 7, wherein: (a) said air distributionconduit has upper and lower portions, said upper portion of said airdistribution conduit being disposed above said at least one porousplate, said lower portion of said air distribution conduit beingdisposed below said porous plate.
 11. An apparatus for use in a filtersystem for filtering water or wastewater; said apparatus comprising: (a)at least one liquid distribution chamber; (b) at least one airdistribution conduit; (c) a porous plate, said at least one liquiddistribution chamber being disposed entirely below said porous plate;(d) at least a portion of said air distribution conduit extends abovesaid porous plate; said air distribution conduit having at least oneexit opening where air exits the at least one air distribution conduit,said at least one exit opening is disposed below said porous plate. 12.An apparatus as set forth in claim 11, further including: (a) anunderdrain block, said liquid distribution chamber being formed in saidunderdrain block.
 13. An apparatus as set forth in claim 12, furtherincluding: (a) an underdrain cap secured to said undedrain block.
 14. Anapparatus as set forth in claim 13, wherein: (a) said air distributionconduit is snap fit to said underdrain cap.
 15. An apparatus for use ina filter system for filtering water or wastewater; said apparatuscomprising: (a) at least one liquid distribution chamber; and, (b) atleast one air distribution conduit having upper and lower portions; (c)a porous plate, said at least one liquid distribution chamber beingdisposed entirely below said porous plate; and, (d) said upper portionof said air distribution conduit being disposed above said porous plate,said lower portion of said air distribution conduit being disposed belowsaid porous plate.
 16. An apparatus as set forth in claim 15, furtherincluding: (a) an underdrain block, said liquid distribution chamberbeing formed in said underdrain block.
 17. An apparatus as set forth inclaim 16, further including: (a) an underdrain cap secured to saidunderdrain block.
 18. An apparatus as set forth in claim 17, wherein:(a) said air distribution conduit is snap fit to said underdrain cap.